Our long-term goal is to develop a novel therapeutic treatment of human prostate cancer (PCA) by sensitizing PCA cells to apoptosis induced by tumor necrosis factor (TNF)-alpha or other cytotoxic agents. Conventional therapeutic treatments of PCA, such as surgery and chemotherapy, have received only limited success. This therapeutic deficiency has largely resulted from the resistance of androgen-independent PCA cells to the killing by TNF-alpha and other cytotoxic agents. The nuclear factor kappa B (NF-kappa B) and the anti-apoptotic genes regulated by this transcription factor play a crucial role in the induction of this resistance. Thus, approaches that target NF-kappa B inhibition in vivo may be highly beneficial when combined with standard cancer therapeutics. The objectives of this Phase I project are to determine whether SN50 and its cyclic analog, small cell-permeable peptides with high inhibitory specificity for NF-kappa B activation, are capable of amplifying the apoptotic activity of TNF-alpha and other cytotoxic agents in human PCA cells. Many studies have convincingly demonstrated that SN50 peptides are highly effective in inhibiting NF-kappa B function in a wide range of biological systems and animal models of disease. In Specific Aim 1, we will examine the inhibitory effects of SN50 peptides on NF-kappa B nuclear translocation in various human PCA cell lines. Electrophoretic mobility shift assay and Western blotting will detect the inhibition of NF-kappa B nuclear translocation and DNA binding activity. In Specific Aim 2, we will determine if inhibition of NF-kappa B nuclear translocation in PCA cells by SN50 peptides results in an increase in apoptosis induced by TNF-alpha and other cytotoxic agents. Increases in the percentage of PCA cells undergoing apoptosis will be quantitated by AnnexinV binding, which measures specific cell membrane changes, and by TUNEL, which measures DNA fragmentation. The accomplishment of the goals of this study will establish a solid basis for the development of a new class of cancer therapeutics, which can significantly augment the efficacy of conventional PCA therapies.